Consider a normally distributed set of test scores with mean $62.76$ and standard deviation $13.66$. What fraction of test scores are less than $58.75$ or greater than $86.75$?
There's only one answer ... I am a bit confused on how to get the correct answer.
HINT: One way to solve the problem is to find separately the fraction of test scores that are less than $58.75$ and the fraction that are greater than $86.75$ and add the results. Another is to find the fraction that are between $58.75$ and $86.75$ and subtract that from $1$. For either approach you’re going to have to convert $58.75$ and $86.75$ to standard units ($z$-scores). For example, $58.75$ is $62.76-58.75=4.01$ points below the mean, so it’s $\frac{4.01}{13.66}$ standard units below the mean: $z=-\frac{4.01}{13.66}$.